Some nouns that end in -um are made plural by changing the –um to –a. which of the following best explains this change?
a. they have greek origins and therefore have irregular plural forms.
b. they have latin origins and therefore have irregular plural forms.
c. they have spanish origins and therefore have irregular plural forms.
d. there are no words that change forms like that in english.

select the best answer from the choices provided

B. They have Latin origins and therefore have irregular plural forms.

Explanation:

There are relatively few words in English ending in -um, because most of those words come from Latin, and Latin wasn't a big contributor to English language as it was to other languages (like French and Spanish, that's why they are called Latin languages). The English -um words are mostly scientific terms.

But for example you have 'datum' (the singular form of 'data') and 'diverticulum' (which does become 'diverticula' in plural form).

halibut, flounder, tuna, and trout are all fish. so your first answer is 1.) fish. and since fish is edible, your next answer would be 3). edible

to describe those fishes more thoroughly, some of those fishes live in fresh water, and some of the fishes live in salt water, and that is not a thing that they all have in common. the question is asking what is common with all of the fish, so answer choices 2). fresh water and 4). salt water are not right.